1. Field of the Invention
The present invention relates to a changeover device incorporated in a looper arm mechanism of an edge stitching sewing machine. More particularly, the invention relates to a device which enables the user to perform one-needle two-thread edge stitching by using a sewing machine primarily applicable for one-needle three-thread edge stitching work. Such two types of edge stitching can be selectively performed by a sewing machine by means of a one-touch changeover device incorporated in the looper mechanism.
2. Description of Relevant Art
When it is necessary to perform one-needle two-thread edge stitching by using a conventional sewing machine of the one-needle three-thread edge stitching type, it has been necessary to disassemble an upper looper and replace it with a hook looper, as well as to replace other associated parts such as a thread guide and the like. Such changeover work is not only troublesome, but requires considerable skill which is quite difficult for an operator employed for ordinary sewing work.
Accordingly, it has been a known practice to separately provide two types of sewing machines, one for one-needle three-thread edge stitching work, and the other for one-needle two-thread edge stitching. However, such separate provision of two different types of sewing machines having substantially the same construction, except for different looper mechanisms, has been found to be uneconomical and objectionable with regard to work efficiency and effective use and adjustment of the floor space to be used in a shop.
Accordingly, there has developed a great need for a novel sewing machine which is capable of performing both one-needle three-thread edge stitching and one-needle two-thread edge stitching by a mere one-touch changeover action.